Kapalabhati breathing (also written Kapalbhati) is one of the Shatkarmas, the latter being a set of Yogic purification or cleansing techniques.
In fact, Kapalabhati is a type of Pranayama, a conscious and rapid breathing technique primarily applied to clean the sinuses, throat, and lungs. As such it’s a kind of meta breathing technique intended to “purify and cleanse the breath” used as a preparation for other types of Pranayamas.
Nevertheless, the Kapalabhati technique is also thought to have a range of health benefits, which include improved internal organ realignment and function, stimulation of the blood circulation, energizing and revitalizing, improvement in concentration and psychological balance, expelling toxins and boosting immunity, among others.
Additionally, Kapalabhati breathing can play a role in Tantra Yoga and in Tantric Sex, used as a technique to improve sexual functions in men such as alleviating Erectile Dysfunction (ED), for semen retention, to control Premature Ejaculation (PE), prolong sexual intercourse (by actively doing Kapalabhati by mouth exhalation during sexual intercourse when approaching an orgasm), and to awaken Kundalini Energy.
The actual technique consists of repeatedly inhaling air passively and naturally into the lungs (through the nostrils) while subsequently actively and forcefully exhaling it with the help of the abdominal musculature (exhalation can be either through the mouth or through the nostrils).
Kapalabhati breathing will cause rapid contraction and release of the abdomen, stimulating the diaphragm and abdominal muscles. While doing the exercise, the circulation of air is typically accompanied by an audible, hissing sound.